The invention relates to a radar apparatus incorporating antenna means, transmitter means connected to the antenna means for generating bursts of radar transmitter pulses, receiver means connected to the antenna means and a doppler filterbank connected to the receiver means for the generation of a range-doppler matrix of echo strength-representing range-doppler elements for each burst, combination means for combining the range-doppler matrices obtained per burst and threshold means for thresholding the combined range-doppler matrices.
A radar apparatus of this kind is known from IEEE Transactions on Aerospace and Electronic Systems, vol. 26, no. 5, September 1990, pp. 754-766; K. Gerlach and G. A. Andrews: "Cascaded detector for multiple high-PRF pulse doppler radars". The radar apparatus described therein makes use of bursts of radar transmitter pulses with a high PRF which introduces ambiguity in the range of a target, but not in the doppler velocity of the target. By combining and thresholding the received echoes for various bursts, it will be possible to unambiguously determine the range of a target and moreover to enhance the detection probability. The method is however only suitable for high-PRF radars.
Said known method is, albeit slightly adapted, also suitable for low-PRF radars which do not give rise to ambiguity in range, but instead in doppler velocity. Low-PRF radars are of little practical significance in view of their incapability of realising adequate clutter suppression.